The present invention relates to industrial controllers for controlling equipment and processes, and in particular to a computer program for use in programming industrial controllers.
Industrial controllers are specialized electronic computers providing high reliability operation and real-time control within well-characterized performance standards. The industrial controllers are normally tailored to a particular application by combining a number of standard components such as a central controller, a network, and input/output (I/O) modules.
The control programs executed by an industrial controller, unlike standard applications executed on conventional computers, are often unique to a particular installation, reflecting the particular requirements of the equipment and machinery subject to control, and the selected components of the industrial controller. For this reason, it is important that the task of writing programs for the industrial controller be simple and efficient, and that the user of the industrial controller be provided with effective tools to write and maintain the specialized control programs.
Many of the variables used in a control program are data from sensors or to actuators communicating with the controlled process or equipment. This data can be identified numerically, for example, as related to an I/O connection point or terminal on the industrial controller. More typically, however, program development programs for control programs allow the programmer to select variable names, or “tags” chosen for mnemonic purposes.
Identifying and naming a large number of input and output variables and linking them to industrial controller components can be quite difficult. For this reason, it is known to provide a program development program that can provide the programmer with information about the types of data provided by the principal hardware components of an industrial controller. As new devices are added, the program development program is updated so that the programmer is always provided with a reference to the types of data available from each component and the meaning of that data. The programmer can use this reference to properly identify variables needed in the program being developed.
A drop in computing costs has caused an increase in low-level devices, such as sensor and actuators, that provide multi-bit data transfers with an industrial controller. Unlike the principle hardware components of the industrial controller, such low-level devices may be manufactured by a large number of different companies and be subject to a much greater variety of function and rates of change of specification. Accordingly, information about the meaning and function of the data from such devices is not easily incorporated into the program development program.